ASHRAE Journal - December 2009 - 56

ASHRAE59–2009 YE A R S JOURNAL Sciences–National Research Council figures, adjusted to 1960 levels). In addition, cost of the activated-charcoal filter must be included. Figuring the amount of air to be treated at 13,200 cfm (to equal 24,000 cfm of outside air), initial cost for 13 filters (at $190 installed including baffles) would be $2470. Total cost of the air-recovery system is $19,270 (line 5). This is partially offset by installed cost for a conventional automatic self-renewing fibrous curtain air filter—$1400 for a 20,000-cfm unit including freight and erection (from National Academy of Sciences–National Research Council figures). In this example six such units would be required, for a total of $8400. Adding the costs shows the air-recovery system costs $790 more than a conventional system (line 6). The cost, of course, depends on the size of a building. As the size increases, the savings of installed air-conditioning equipment mount, tending to favor the air-recovery system. For a smaller building, the converse is true, and the cost difference for the proposed air-recovery system will assume a larger proportion of the amount for air-handling equipment. However, any negative balance is offset by operating savings. OPERATING COSTS During a Chicago summer there will be 620 hr of fullload air-conditioning operation (1959 ASHRAE Guide, Table V, page 730). To operate 60 ton of air-conditioning equipment costs 1.5 cents a ton an hr (based on Carrier Corporation data). Therefore, cost of each operating ton during the 620 summer hours would be $9.30. Water costs are figured at 32.8 cents a ton a year (page 95, Modern Air Conditioning, Heating and Ventilating by Carrier, Cherne and Grant). Annual repairs, refrigerant and lubricants cost for each ton is $1.738 (based on 1959 ASHRAE Guide, Table IV, page 729, adjusted for 1960). Total for power, water and supplies is $11.37 a ton each year. Operating cost for the 60.5 ton cooling capacity of the conventional system is $687.89, compared to $309.26 to operate cooling equipment for the air-recovery system (line 7). Average Chicago winter temperature is 37.6°F (1958 ASHRAE Guide, Table I, page 263). Operating the building 55 hr a week for the 31 weeks from October through April would total 1705 hr. 56 ASHRAE Journal To heat 1000 cfm of 37.6°F air to 70°F takes 35,000 Btu an hr (1959 ASHRAE Guide, formula 5, page 144). For the 1705 hr of winter weather the heating system would require 9,675,000 Btu per 1000 cfm. Figuring natural gas at 1021 Btu a cu ft (Table VI, page 475, 1959 ASHRAE Guide) the boiler needs 58,400 cu ft to heat 1000 cfm during the 31-week winter season. If the gas rate is 85 cents a cu ft, it costs $49.64 to heat this 1000 cfm. Heating costs for the conventional system are $1191.36. Since an air-recovery system would save 13,200 cfm, heating costs for this system are $536.11 (line 8). Annual operating costs for a conventional automatic selfrenewing fibrous curtain air filter (using National Academy of Sciences–National Research Council figures) would be: labor (8 hr at $3), four rolls of media (at $30 each) and current ($6) to total $150 for a 20,000 cfm unit. For six such units the annual operating cost would be $900 (line 9). Operating costs for an air-recovery system (from National Academy of Sciences–National Research Council figures) include two rectifiers (at $15 each), 10 gal of oil (at $1 a gal) and 24 hr of labor at $3, plus $13 for current to total $125. Since this is for one 20,000 cfm unit, cost of operating six such units yearly is $750. In addition, the electronic air cleaner will require regular washing. In this example the cleaner is 7 cells high and 19 ft wide. Each cell tier requires 61/4 gpm, or 44 gpm for this installation. Complete washing takes 30 sec for each ft, or a total of 10 min for the 19 ft wide equipment. With 44 gpm used for 10 min, the total requirement for each washing cycle is 440 gal. Washing the unit every 2 weeks requires 11,440 gal a year. Figuring water at 90 cents for 1000 gal, annual water cost is $10.30. To heat this water from 40°F to the required 140°F takes 1.66 cu ft of gas for each gal. Total gas required each year then is 18,900 cu ft. At 85 cents per 1000 cu ft, annual water-heating cost is $16.14. Total washing water costs are $26.44 annually. Operating costs (labor, freight, recharged cells) for an activated-charcoal filter come to $21.23 for 1000 cfm or $275.99 for this example. Total annual operating costs are $776.44 plus $275.99 or $1052.43 (line 10). Therefore, initial cost of an air-recovery system is more than offset during the first year. After that, operating savings are around $900 a year in the example (line 11). But economic justification of an air-recovery system is based on more than original and operating cost coma s h r a e. o rg December 2009

ASHRAE Journal - December 2009

Table of Contents for the Digital Edition of ASHRAE Journal - December 2009

ASHRAE Journal - December 2009
Contents
Commentary
Industry News
Letters
Meetings and Shows
ASHRAE Building EQ Program
Feature Articles
A Closer Look at Chiller Ratings
Cooling With Less Air: Using Underfloor Air Distribution and Chilled Beams
Cooling Concrete: Containerized Water Chilling Plant
Geothermal for Community Center
Anniversary Feature: Air-Recovery System Versus Conventional Air Conditioning
Technical Topics
New Product Preview
Products
Emerging Technologies
Washington Report
People
Special Products
2009 Feature Articles Indices
Classified Advertising
Advertisers Index
ASHRAE Journal - December 2009 - ASHRAE Journal - December 2009
ASHRAE Journal - December 2009 - Cover2
ASHRAE Journal - December 2009 - 1
ASHRAE Journal - December 2009 - 2
ASHRAE Journal - December 2009 - Contents
ASHRAE Journal - December 2009 - 4
ASHRAE Journal - December 2009 - Commentary
ASHRAE Journal - December 2009 - Industry News
ASHRAE Journal - December 2009 - 7
ASHRAE Journal - December 2009 - 8
ASHRAE Journal - December 2009 - 9
ASHRAE Journal - December 2009 - 10
ASHRAE Journal - December 2009 - Letters
ASHRAE Journal - December 2009 - 12
ASHRAE Journal - December 2009 - 13
ASHRAE Journal - December 2009 - 14
ASHRAE Journal - December 2009 - 15
ASHRAE Journal - December 2009 - Meetings and Shows
ASHRAE Journal - December 2009 - 17
ASHRAE Journal - December 2009 - Feature Articles
ASHRAE Journal - December 2009 - 19
ASHRAE Journal - December 2009 - 20
ASHRAE Journal - December 2009 - 21
ASHRAE Journal - December 2009 - A Closer Look at Chiller Ratings
ASHRAE Journal - December 2009 - 23
ASHRAE Journal - December 2009 - 24
ASHRAE Journal - December 2009 - 25
ASHRAE Journal - December 2009 - 26
ASHRAE Journal - December 2009 - 27
ASHRAE Journal - December 2009 - 28
ASHRAE Journal - December 2009 - 29
ASHRAE Journal - December 2009 - 30
ASHRAE Journal - December 2009 - 31
ASHRAE Journal - December 2009 - 32
ASHRAE Journal - December 2009 - 33
ASHRAE Journal - December 2009 - Cooling With Less Air: Using Underfloor Air Distribution and Chilled Beams
ASHRAE Journal - December 2009 - 35
ASHRAE Journal - December 2009 - 36
ASHRAE Journal - December 2009 - 37
ASHRAE Journal - December 2009 - 38
ASHRAE Journal - December 2009 - 39
ASHRAE Journal - December 2009 - 40
ASHRAE Journal - December 2009 - 41
ASHRAE Journal - December 2009 - Cooling Concrete: Containerized Water Chilling Plant
ASHRAE Journal - December 2009 - 43
ASHRAE Journal - December 2009 - 44
ASHRAE Journal - December 2009 - 45
ASHRAE Journal - December 2009 - 46
ASHRAE Journal - December 2009 - 47
ASHRAE Journal - December 2009 - Geothermal for Community Center
ASHRAE Journal - December 2009 - 49
ASHRAE Journal - December 2009 - 50
ASHRAE Journal - December 2009 - 51
ASHRAE Journal - December 2009 - Anniversary Feature: Air-Recovery System Versus Conventional Air Conditioning
ASHRAE Journal - December 2009 - 53
ASHRAE Journal - December 2009 - 54
ASHRAE Journal - December 2009 - 55
ASHRAE Journal - December 2009 - 56
ASHRAE Journal - December 2009 - 57
ASHRAE Journal - December 2009 - 58
ASHRAE Journal - December 2009 - 59
ASHRAE Journal - December 2009 - 60
ASHRAE Journal - December 2009 - 61
ASHRAE Journal - December 2009 - Technical Topics
ASHRAE Journal - December 2009 - 63
ASHRAE Journal - December 2009 - 64
ASHRAE Journal - December 2009 - New Product Preview
ASHRAE Journal - December 2009 - 66
ASHRAE Journal - December 2009 - 67
ASHRAE Journal - December 2009 - 68
ASHRAE Journal - December 2009 - 69
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ASHRAE Journal - December 2009 - 112
ASHRAE Journal - December 2009 - 113
ASHRAE Journal - December 2009 - Products
ASHRAE Journal - December 2009 - 115
ASHRAE Journal - December 2009 - 116
ASHRAE Journal - December 2009 - Emerging Technologies
ASHRAE Journal - December 2009 - Washington Report
ASHRAE Journal - December 2009 - 119
ASHRAE Journal - December 2009 - People
ASHRAE Journal - December 2009 - Special Products
ASHRAE Journal - December 2009 - 2009 Feature Articles Indices
ASHRAE Journal - December 2009 - 123
ASHRAE Journal - December 2009 - 124
ASHRAE Journal - December 2009 - 125
ASHRAE Journal - December 2009 - Classified Advertising
ASHRAE Journal - December 2009 - 127
ASHRAE Journal - December 2009 - Advertisers Index
ASHRAE Journal - December 2009 - Cover3
ASHRAE Journal - December 2009 - Cover4
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